This invention relates to the measurement of the gas content in substances and more particularly to the measurement of such gas content in inorganic conductive and semiconductive elements and compounds having a low sublimation temperature.
The gas content in metals can be measured using the well known high-vacuum gas extraction method or through gas extraction in a protective gas also referred to as the carrier gas method. These methods and the apparatus developed in connection therewith are essentially limited to substances whose sublimination temperature is close to or above 1000.degree.C, i.e., to high melting metals or their alloys. When using the high vacuum extraction method for example, and with a mass spectrometer as an analyzer, the material to be investigated is melted. The degassing temperature is short and sufficiently high to ensure an adequately high diffusion velocity of all components of interest in the melt, with the evaporation rate of the material being investigated low during the degassing. With this method, it is theoretically possible to detect qualitatively and quantitatively all the components given off by the sample using a single measurement. However, these criteria required for gas content determinations using this method are met only by materials having a sublimation temperature from 1000.degree.C on up. The high vacuum extraction method is not suitable for substance having a low sublimation temperature such as those having sublimation temperature from 200.degree.C on up. Furthermore, use of the carrier gas method for determination of the gas content in such substances is not possible since, at the necessary high temperature, the sublimation rate of the sample to be investigated is still too high.
Thus, it can be seen that there is a need for a method and apparatus which permits making reliable qualitative and quantitative measurements of the gas content in inorganic conductive and semiconductive elements and their compounds having a low sublimation temperature in a simple manner.